A 20,000-acre fire burning on the Kenai Peninsula made its way into a 300-home subdivision about 14 miles east of Ninilchik, fire officials said.

No injuries had been reported, but an unknown number of structures - both vacation cabins and permanent homes - were destroyed.

The Ninilchik 40 Subdivision and the Caribou Hills Recreation Area were ordered evacuated, but Kris Eriksen, a Division of Forestry spokeswoman, said some people remained in their homes.

"We can't make people leave," she said. "There's fire creeping around their homes."

Officials worked Friday morning to assess damage. The Caribou Hills Fire remained 14 miles east of Ninilchik and was not threatening coastal towns.

Eriksen said the area is riddled with highly flammable beetle-killed trees and black spruce.

The fire has spread several miles into the south side of Deep Creek drainage, Eriksen said, something firefighters had been struggling to prevent.

"When fire gets into drainages, they sort of chimney down because there's a lot of fuel in them," she said.

Firefighters were hoping the fire would not cross to the north side, where structures are located.

The blaze - spewing out a 40,000-foot column of smoke - also spread on its northeast flank and threatened cabins in the recreation area, Eriksen said.

The fire began Tuesday when sparks from a grinder being used to sharpen a shovel fell into dry grass, Eriksen said.

More than 120 firefighters were battling the fire, Eriksen said.

"It's amazing the amount of energy this thing is putting off," she said. "It has a lot of fuel."

The National Weather Service predicted isolated showers for Friday, with highs in the mid-60s.

State fire bosses called up crews from as far away as Anchorage and Fairbanks to fight the fire.

Smoke reaching Anchorage prompted the municipal Department of Health and Human Services to declare a health advisory. Officials said air quality varied throughout the city from moderate to unhealthy.

To the north, lighting and human activity sparked 28 fires in the Susitna Valley by late Thursday.

Only two were still of major concern: the 55-acre Yetna Fire and the Su River Fire.

The Su River Fire, about a quarter mile south of Trapper Lake, had burned 5,500 acres by late Thursday and was threatening at least 40 cabins, Weaver said.

Its smoke drifted across the Parks Highway, raising fears Thursday afternoon that the fire would spread across the barrier. Officials said the danger at the time was minimal.

The state has ordered 10 hotshot crews from the lower 48 states, along with other needed firefighting equipment. When they arrive, they may be sent anywhere in the state, said spokesman Matt Weaver of the state Division of Forestry.

"We're probably going to have a very busy season," said Rusty Belanger, an assistant state fire marshal. "I don't think we've even hit the tip of the iceberg yet."

He said the fire season is off to an early start in part because of light winter snowfall and dry, hot conditions.